Hyperthyroidism Symptoms

  • Symptoms

    Because thyroid hormones affect almost every tissue in the body, a wide range of symptoms may occur with hyperthyroidism Table 02. Thyroid hormones increase the body's metabolic rate, speeding up the body's functions in much the same way as a strong stimulant would. The resulting symptoms include nervousness, irritability, increased perspiration, thinning of the skin, brittle hair, muscular weakness, tremors, heart palpitations, rapid heartbeat, frequent bowel movements, weight loss, and changes in menstrual flow.

    Heart problems, especially palpitations, rapid heartbeat, or abnormal heart rhythms, occur most frequently in older adults. These older patients may also become weak, sleepy, confused, or depressed.

    Table 2.  Symptoms of Hyperthyroidism

    General symptoms
    Nervousness and irritability
    Heart palpitations or rapid heartbeat
    Difficulty breathing
    Changes in menstrual flow
    Changes in heat tolerance or sweating
    Impair fertility
    Weight loss
    Mental disturbances
    Sleep disturbances
    Changes in appetite
    Frequent bowel movements
    Fatigue and muscle weakness
    Thyroid enlargement
    Sudden paralysis
    Symptoms specific to Graves' disease
    Changes in vision or tolerance to light
    Eye irritation
    Double vision
    Bulging or protruding eyes
    Swelling or thickening of the skin in front of the shins.

    *Adapted from the ACCE Clinical Practice Guidelines for the Evaluation and Treatment of Hyperthyroidism and Hypothyroidism. Endocrine Practice 1995; 1(1)

    In addition to other symptoms of hyperthyroidism, patients with Graves' disease sometimes experience inflammation of tissues around the eyes. In Graves' disease, the eyes may appear to be enlarged because the upper eyelid becomes elevated. Less frequently, the eyes may bulge from their sockets because of tissue inflammation behind the eyeball. Inflammation affecting the muscles that control eye movement may prevent the eyes from moving properly, resulting in double vision. The cause of these symptoms is unknown, and their severity is not determined by the amount of excess thyroid hormone produced by the body. Serious or permanent damage to the eyes, however, occurs only rarely.

    A very small percentage of the people with Graves' disease also develop a lumpy, itchy reddish thickening of the skin in front of their shins. The cause of this symptom and the reason why it is limited to so few patients with Graves' disease is unknown.

    The symptoms of hyperthyroidism generally develop over time. In most cases, thyroid hormone production increases gradually over time. At first, the symptoms may be mild and attributed to stress, anxiety, or other normal life events. As the thyroid hormone production accelerates, however, the symptoms become more pronounced. In Graves' disease, changes in the eyes sometimes appear before other symptoms.

  • Risk Factors

    Although the genetic basis is not well understood, inheritance plays some role in development of Graves' disease.

    Hyperthyroidism occurs frequently in older adults. In many cases, hyperthyroidism in older adults has few prominent symptoms. The enlarged thyroid and nervousness or heat intolerance commonly reported by younger patients are often missing. Weight loss and weakness may be attributed to age or other conditions. As a result, hyperthyroidism may be overlooked. Many physicians now recommend regular screening with a blood test to identify hyperthyroidism in older adults.

    Smoking increases the possibility that Graves' disease will involve the eyes. Therefore, if you smoke, quit.

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